The treaty that formally ended World War I was the Treaty of Versailles, signed on June 28, 1919. The treaty was negotiated at the Paris Peace Conference, with the Allied Powers, particularly France, Britain, and the United States, imposing heavy reparations and territorial losses on Germany. The document aimed to prevent future conflicts by redrawing national boundaries and establishing the League of Nations to promote international cooperation. However, the treaty's harsh terms led to economic hardship and political instability in Germany, contributing to the rise of extremist movements and the onset of World War II, thus sparking debates over its long-term impacts.